In general, a detector detecting the status of displacement of an object by the Doppler effect requires a high frequency input signal from an oscillation source operated at a high frequency to update the status of displacement of the object. Since it is difficult to process a high frequency signal with a digital process, an analog process is usually used to process the signal. Therefore, the signal is affected by flicker noise easily, the signal noise ratio (SNR) is reduced seriously, and the difficulty of subsequent digital signal processing (DSP) is increased. Furthermore, since the oscillation source is operated at a high frequency (e.g. around 10 GHz) which cannot be decreased, the power consumption of the oscillation source cannot be decreased easily. A solution with lower power consumption and smaller effect by flicker noise is required in this field.